Multiple shell grab



Jan; 21, 1958 F. MENDE 2,820,664

MULTIPLE SHELL GRAB Filed May 26, 1963 5 Sheets-Sheet 1 i.ZYIIIIIIIIIIIIIIIJ'IIII,

INVENTOR. Frz i'z Manda,

BY PMG Pau A TTORNEYS.

Jan. 21, 1958 F. MENDE 2,820,664

MULTIPLE SHELL GRAB Filed May 26, 1953 3 Sheets-Sheet 2 FIG: 5 FIG 6INVENTOR. Fri i'zliefide,

.pwi PM A TTORNEYS.

Jan. 21, 1958 F. MENDE 2,820,664

MULTIPLE I SHELL GRAB Filed May 26, 1953 3 Sheets-Sheet 3 INVENTOR-Frzzz Manda,

BY PM Paul.

A TTORNEYS.

MULTIPLE SHELL GRAB Fritz Mende, Kettwig, Germany Application May 26,1953, Serial No. 357,443

Claims priority, application Germany October 22, 1952 8 Claims. (Cl.294-111) This invention relates to a grab, and more particularlyconcerns a grab of the multi-shell type which is adapted to be suspendedfrom the boom of a crane, for example, for lifting wide varieties ofobjects such as ingots, stones, beams, girders and metal shavings oreven bars and slabs. In grabs of this character the shells and shelloperating mechanisms are subjected to very great stresses, particularlywhen bulky loads are to be picked up. Moreover the grab is frequentlyrequired to pick up objects of irregular form, or objects which arepiles up in 'an irregular fashion; this imposes even greater stressesupon certain parts of the grab. Moreover one or more grab shells maystrike a heavy or substantially immovable object as the grab is beingclosed, or objects may be trapped between the shells, and this subjectsthe shells and working parts to stresses which are sometimes sutii'cientto cause damage.

It is accordingly an object of this invention to provide a multipleshell grab of the character indicated, wherein the shell members havecapacity to resist excessive stresses. Another object is to provide agrab of this character wherein the grab shells have capacity to yield tosuch stresses. Another object of this invention is to provide a multipleshell grab having a strong hinged connection between the shells and themechanism which operates the shells, such connection simultaneouslybracing the shells. Other objects and advantages of this invention,including the simplicity and economy of the same and the strength of thegrab in proportion to its weight, will further become apparenthereinafter and in the drawings whereof:

Fig. 1 represents a view in perspective showing a multiple shell grabembodying features of this invention, some of the shells at the rear ofthe drawing being removed for the sake of clarity;

Fig. 2 represents a vertical sectional view of the grab shown in Fig. 1,certain parts being broken away and shown in section in order toillustrate important details;

Fig. 3 represents a plan view of the base of the grab, taken asindicated by the lines and arrows IIIIII which appear in Fig. 2;

'Fig. 4 represents a section view taken as indicated by the lines andarrows IVIV which appear in Fig. 3;

Figs. 5, 6 and 7 represent sectional views taken as indicated by thelines and arrows VV, VIVI and VII-VII which appear in Fig. 2;

Fig. 8 reprseents a view in vertical section similar to Fig. 2 showingthe same grab provided with a fluid cylinder grab-actuating means;

Fig. 9 is a plan view of the grab shown in Fig. 8 as seen in thedirection of lines and arrows IXIX, certain parts being shown insection; and

Figs. 10 and 11 are sectional views taken as indicated by the lines andarrows, X-X and XI-XI, which appear in Figs. 9 and 8, respectively.

Turning now to the specific embodiment of the invention selected forillustration in the drawings, the number (it) designates a grab headhaving a cylindrical form,

Patented Jan. 21, 1958 ice suspended from above by a rope or cable 11.Means are provided such as a hoist or the like (not shown) for raisingand lowering the head 10. Suspended from another rope or cable 12, whichmay also be pulled up or let down by a crane hoist, independently ofcable 11, is a substantially cylindrical base 13. Pivotally mounted atequally spaced points around the periphery of base 13 are a plurality ofgrab claws or shells 14. The shells 14 are linked to the grapple head 10by a plurality of rigid link bars 15 the upper ends of which are pivotedto the head 10 at equally spaced points around the periphery of the head10. The lower ends of link bars 15 are slidably pivoted to the outeredges of the grapple shells 14 at points eccentric to the pivotalconnection between the shells and base 13, as will further be described.

The cable .12 is trained around a series of pulleys carried on the head10 and on the base 13 whereby the base may be raised and lowered withrespect to the head. When power is applied by means of a hoist or otherapparatus to raise the cable 12, the base 13 is lifted toward the head10, and the link bars 15 coact with the base and head to swing theshells 14 downwardly to their closed position shown in solid lines inFig. 2. The weight of base 13 together with the weight of the memberscarried thereon is suflicient to open the shells 14 by gravity actionalone when the cable 12 is lowered, the base 13 descending to theposition shown in dotdash lines in Fig. 2.

The head 10 is a substantially cylindrical beam having upper and lowerflanges 20, 21. Fixed to the beam extending vertically between flanges20, 21 are pairs of cars 22 each pair of which is apertured and carriesa transverse sleeve 23, as appears more particularly in Figs. l, 2 and5. A pivot pin 24, of much less diameter than the aperture or the insidediameter of sleeve 23, extends longitudinally through sleeve 23.Substantial clearance is thus provided between pin 24 and sleeve 23,.permitting the longitudinal axis of the pin to rock inside the sleeve.

Each link bar 15 includes apair of channel bars 30 fixed at their upperends to the pivot pin 24. The channel bars 39 have capacity to rocktogether with the pin 24, in the plane of the pin. The channel bars 30are reinforced by upper and central transverse I-beams 31, 32 and by alower cross beam 33 having an inclined web 34 (see particularly Figs. 1and 2) adjacent the convex outer edge of the adjacent shell 14. Eachside of the link bar 15 is reinforced by angle plates 35, 35 (see Figs.1, 2 and 7) which have upper and lower inclined portions.

The base 13 consists of upper and lower plates 40, 41 (see particularlyFigs. 1-3) which are substantially circular in form. They are centeredon the perpendicular axis extending through the center of head 10.Plates 4t), 41 are welded or otherwise aflixed to a plurality ofvertical web plates 42 which are arranged in pairs at equally spacedpoints around the peripheral edge of base 13. The lower plate 41 isnotched at 43 between the web plates 42. Web plates 42 have alignedholes 44 receiving pivot shafts 45 on each of which a shell 14 is hungin a manner further to be described.

Each grab shell 14 consists of a curved metal plate 50 to the convexface of which is welded (or otherwise attached) a central perpendicularsaddle plate 51. A crescent shaped side plate 52 (see also Fig. 6) iswelded or otherwise afiixed to or even formed integrally with each sideof saddle plate 51 and is affixed to the curved plate 50. Thus, eachshell 14 has two crescent shaped side plates 52 which reinforce andrigidity the entire shell structure.

The upper end of each saddle plate 51 is apertured at 53 and thepivot'shaft -45 extends through the aperture to pivot the shell 14 tothe ase 13. As appears more particularly in Fig. 4 of the drawings, thebearing 54 is rounded at the edge of aperture 53 permitting the entireshell 14 to rock laterally in.the plane ofthe pivot shaft 45. This is animportant. and advantageous feature, of the invention, as will furtherappear. f 1

, The tips of the shells 14-are reinforced by indented plates 57 whichare suitably welded to the saddle member 51. The-tips and lateralborders of theshells are'hardened as indicated M58 in Fig. 2, preferablybyany hard facing operation such as applying a chrome electrode, forexample. These surfaces may otherwise be processed by the use of armoredplate or. speciallyhardened materials.

However for heavy duty grabs, particularly if they are intended forhandling bulky loads, such as steel scrap and the like, the specificconstruction shown in the drawings is distinctly preferred.

Preferably the ridge portion 56 of the saddle 51 has a wall thickness ofabout 3 to 4 times the thickness of a single web plate such as saddle 51thereby strengthening the oblong slot which serves as a sliding planefor the base of the link bar. I a

The grab shown in Figs. 8-11 is similar to the grab just described, andlike parts bear similar numbers. However the grab shown in Figs. 8-11 isactuated by means of a pneumatic cylinder 100 which is pivotallysuspended However it is preferred to harden the surface by applying acoating of weld metal from a chrome vanadium or other chrome bearingelectrode.. The shells lean be provided with a plurality of bolt'holes'.for attaching supplemental scoop bowls or plates 59, one of which isshown attached in Fig. 1. With bowls 59 attached, the 'shells formfanenclosed space (an ellipsoid of rotation) when they are brought to theposition shown insolidlines inFig. 2. I The grab may then be operated asa s'coo'por digging device for excavating sand or dirt or other finelydivided materials, or for unloading vessels carrying ores, scrap, clayor other materials. The scoop plates'59 are readily detachable by oneperson in a short time. Other suitable means may be providedforattaching scoop plates 59, as will readily be apparent, It will beappreciated that other means may be provided for attaching the bowls 59to the shells, such as groovedor flanged'means whereby the bowls mayreadily slide on and off of the shells but are frictionally maintainedthereon.

Each shell 14. is actuated, through-a sliding pivotal connection, by thecorresponding linkbar Saddle plate 51 is slotted at 55, the slot 55being located in a ridge portion 56 disposed outwardly of and eccentric'to' the pivot shaft 45. The slotted area is reinforced by a pair ofslotted reinforcing plates 60, 60. The lower end of the link bar 15carries a roller shaft 61 which bridges across between the lower ends ofchannel bars 30. A crowned roller 62 is carried by shaft 61 extendingthrough the slot '55. By reason of the curvature of the crowned roller,the entire shell 14 has capacity to rock laterally with respect to theroller and link bar 15.

In operation, the grab is suspended on cable 11 with "cable12 relaxedand the shellsopen as in Fig. 1. The

grab is lowered on top of the object or objects to be lifted. The bottomplate of base 13 rests'onthe objects. Cable :12 is then pulled tight andthe grab shells are gradually closed by the combined action of base 13,which lifts the shape of the claws or shells and to the manner inwhich Ithey are actuated through the pivoted slotted linkage heretoforedescribed.

The aforementioned pivot points are subjected to great for limitedrockingmovement with respect to the base stresses, particularly whenbulky or heavy loads are to I be picked up. When anv individual grabshell strikes an unusually heavy substantially immovable object duringthe closing operation, it lags behind the other shells to a limitedextent by reason of the slotted pivoted structure, protecting the grabshells and even their pivoted connections to the link bars and to thebase, against excessive stresses. Moreover the entire shell togetherwith its associated link bar has capacity to rock laterallywhen anunusual resistance is encountered, or when material is mornentarilytrapped between adjacent shells, thus protecting the parts and theirpivoted connections. 7

It will be appreciated that other equivalent means may be utilized toaccomplish the results described above. For example the pivotedconnection between the grab shells and the corresponding link bars mayconsistof rope pulleys whichare arranged at the bottom ends of the linkbars and guided on flanges on the backs of thegrab shells.

use in digging shafts for mines and the like.

from a channel iron frame 101. Attached to frame 101 is a four-way valve102 connected to the upper and lower ends of cylinder by flexible tubing103, 104. A piston 105 attached to piston rod 106 reciprocates incylinder 100, the rod 106 being pivotally connected at its lower end tothe base 13.. Means are provided (not shown) for compressing air and forconducting it through a flexible tube or hose 107 to the valve 102.

Referring to Figs. 8,9 and 10, the cylinder 100 has an upstanding car110 which extends between a pair of depending ears, 111, 111 carried bythe frame 101. The ears are apertured to receive a pivot pin 112. Theaperture through the upstanding ear 110 has a rounded bearing surface113, as shown in Fig. 10, which is an important feature of theinvention, permitting a limited rocking movement of cylinder 100 withrespect, to frame 101. The spacing between ears 111, 111 is sufiicientto permit this rocking movement. Y

As appears in Fig. 11, piston rod 106 has capacity 13, by virtue of therocking pivot connection including spaced ears 114, 114 attachedto thebase, ear 115 attached to piston rod 106, pivot pin 116, and the roundedbearing surface 117 of the opening through ear 115.

The operation of the grab shown in Figs. 8-11 will be apparent. Assumingthe grab shells 14 are in their opened position (as shown in dot-dashlines in Fig. 8), the operator sets the four-way valve 102 toinject airunder pressure into the bottom of cylinder 100 through tube 104. The airfrom above piston 105 is exhausted through tube 103 and through anexhaust pipe 120 on four-way valve 102. The piston and base 13 are.lifted, raising the grab shells to the position shown in solid lines inFig. 8, thereby closing the grab shells. The shells are opened bysetting four-way valve 102 to introduce air under pressure into cylinder100 through tube 103, the exhaust air passing out through tube 104 andexhaust pipe 120, as will be apparent. The internal construction offour-way valve 102 is well known and conventional, and is not shown.

The pneumatic driven grab of Figs. 8-11 is advantageous for removingrock blasted from a vertical mine shaft and for other similar or specialuses. The pneumatic actuating mechanism provides a positive, rapidclosing action enabling the grab shells to dig into large, heavy rocksand the like. Yet the actuating mechanism has capacity to rock and topivot with respect to the base to minimize stresses. While a pneumaticactuating mechanism is shown, other fluids may be substituted for air,such as water, glycerine, oil or the like, and a proper reservoir may beprovided for re-use of hydraulic or other fluid materials.

' Accordingly it will be appreciated that the multiple shell grab inaccordance with this invention is ideally suited for the movement ofscrap of any sort, ore, limestones, basalt and even girders or otherbulky material, for instance logs, pig iron and the like, forwell-digging, and also for dredging below the surface of water. It isalso, as heretofore described, capable of advantageous of substantially100% filling each time the shells are closed, even when the grabisseverely tilted While the It is capable shells or claws shown in thedrawings are cable-operated, they may readily be motor-operated ifdesired.

It will be appreciated that the word shell as employed herein refers torelatively narrow shells such as claws or fingers and also refers torelatively broad blades or scoops, all as disclosed herein.

Although this invention has been described in detail with reference toone specific embodiment adapted for specific purposes, it will readilybe apparent that the device has other uses, that the form of theapparatus may be considerably varied, and that equivalent structures andmaterials may be employed for accomplishing the same results. Suchchanges, including reversals of parts and the use of certain features ofthe invention independently of the use of other features, are within thespirit and scope of the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A multiple shell grab comprising a head member, a base member in theform of a platform, a power cylinder pivoted to one of said membershaving a driven shaft pivoted to the other of said members with capacityto move said members toward and from one another, a plurality of morethan two shells pivoted to said platform, means for swinging said shellsabout their pivots to open and close the shells in response to saidrelative movement of said head and base members, the pivotal connectionsbetween the cylinder, shaft, head member and base member including looseconnecting means whereby the cylinder and shaft have capacity forlimited rocking movement with respect to said head and base members atan angle to their pivotal movement.

2. The multiple shell grab defined in claim 1 wherein the power cylinderis pivoted to the head member and the shaft is pivoted to the basemember, and wherein pneumatic couplings are connected to the cylinder toactuate the shaft.

3. The multiple shell grab defined in claim 1 wherein the pivotedconnections include plate members which are apertured and linkedtogether by a pivot shaft, and wherein one of the apertures has arounded edge adjacent the shaft.

4. A multiple shell grab, in combination, a head member; a base member;means for moving said members toward and away from each other; aplurality of shells mounted on said base member for swinging movementrelative thereto between open and closed positions; a plurality of barmembers; and attaching means for pivotally attaching each bar member atone end thereof to said head member and for so attaching each bar memberat the other end thereof to one of said shells at a point thereon spacedfrom the point at which the respective shell is swingably mounted onsaid base member that said other end of each bar member is pivotableabout a pivot axis relative the shell to which it is attached and isslidable relative thereto between predetermined limits in a directiontransverse to said pivot axis, whereby an individual shell may lagbehind upon encountering strong resistance as the shells are closed.

5. A multiple shell grab, comprising, in combination, a head member; abase member; means for moving said members toward and away from eachother; at least three shells mounted on said base member for swingingmove ment relative thereto between open and closed positions, each shellbeing swingable about a respective swinging axis; a plurality of barmembers corresponding in number to the number of shells; and attachingmeans for so attaching each bar member at one end thereof to said headmember that said one end is pivotable relative to said head member abouta first pivot axis substantially parallel to the swinging axis of thecorresponding shell and for so attaching each bar member at the otherend thereof to the corresponding shell at a point thereon spaced fromthe swinging axis thereof that said other end of each bar member ispivotable relative to the corresponding shell about a second pivot axissubstantially parallel to said first pivot axis and is slidable relativeto the respective shell between predetermined limits in a directiontransverse to said second pivot axis, whereby an individual shell maylag behind the other shells upon encountering strong resistance as theshells are closed.

6. A multiple shell grab, comprising, in combination, a head member; abase member; means for moving said members toward and away from eachother; a plurality of shells; mounting means for mounting said shells onsaid base member for such swinging movement relative thereto betweenopen and closed positions that each of said shells has capacity forlimited lateral movement at an angle to its swinging movement while saidshells are being closed; a plurality of bar members; and attaching meansfor pivotally attaching each bar member at one end thereof to said headmember and for so attaching each bar member at the other end thereof toone of said shells at a point thereon spaced from the point at which therespective shell is swingably mounted on said base member that saidother end of each bar member is pivotable about a pivot axis relativethe shell to which it is attached and is slidable relative theretobetween predetermined limits in a direction transverse to said pivotaxis; whereby an individual shell may lag behind upon encounteringstrong resistance as the shells are closed.

7. The combination defined in claim 6 wherein said attaching means forattaching each bar member at said other end thereof to the correspondingshell includes an elongated slot and pivot-pin arrangement.

8. A multiple shell grab, comprising, in combination, a head member; abase member; means for moving said members toward and away from eachother; at least three shells; mounting means for so mounting said shellson said base member for such swinging movement relative thereto betweenopen and closed positions that at least one of said shells has capacityfor limited lateral movement at an angle to its swinging movement whilesaid shells are being closed; a plurality of bar members correspondingin number to the number of shells; and attaching means for pivotallyattaching each bar member at one end thereof to said head member and forso at taching each bar member at the other end thereof to one of saidshells at a point thereon spaced from the point at which the respectiveshell is swingably mounted on said base member that said other end ofeach bar member is pivotable about a pivot axis relative the shell towhich it is attached and is slidable relative thereto betweenpredetermined limits in a direction transverse to said pivot axis,whereby said one shell may lag behind the other shells upon encounteringstrong resistance as the shells are closed.

References Cited in the file of this patent UNITED STATES PATENTS247,829 Johnson Oct. 4, 1881 921,821 Frazier et al May 18, 1909 925,018Ouchterlony June 15, 1909 1,820,118 Canulette Aug. 25, 1931 2,652,280Billings Sept. 15, 1953 2,715,787 Williams Aug. 23, 1955 FOREIGN PATENTS60,501 Denmark Jan. 11, 1943 302,091 Great Britain Dec. 13, 1928

